1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same.
Priority is claimed on Japanese Patent Application No. 2009-171462, filed Jul. 22, 2009, the content of which is incorporated herein by reference.
2. Description of the Related Art
In general, the process for manufacturing a semiconductor device may include the following final process. Circuit connection information is updated. Particular circuit operations are performed in order to recover operational faults having been caused by a manufacturing process as well as to switch circuit functions.
A technique has been known to provide fuses in a semiconductor product. The fuses changes circuit connections. A particular external signal is input into the semiconductor product, in order to change the conductive states of the fuses for allowing the semiconductor product to perform desired circuit operations.
The fuse having the above-described function is known as an antifuse which will be referred to as an electrical fuse. The antifuse may be placed in a non-conductive state in an initial state and may be changed to a conductive state in response to an external signal input.
Japanese Unexamined Patent Application Publication No. 2005-260217 discloses that a technique has been known to form a fuse element having substantially the same structure as a MOS type transistor and to change the conductive state by the presence/absence of breakdown of a gate insulating film when the above-described antifuse is formed on a semiconductor device having the MOS type transistor.
Japanese Unexamined Patent Application Publication No. 2007-194486 discloses that when the antifuse is formed in combination with the MOS type transistor, it is important to avoid any further increase in the number of manufacturing processes necessary to form antifuse elements. In this point of view, a method of forming an antifuse element has been proposed. The common process can form both the antifuse element and a MOS type transistor.
Japanese Unexamined Patent Application Publication No. 2007-194486 discloses that the antifuse element does not affect a resistance value after a connection by setting both a conductivity type of gate electrode and a conductivity type of region facing through the gate insulating film to the same conductivity type such as P-type. This has been made in view of the fact that a PN junction is formed upon connection when the gate electrode has a conductivity type different from a lower region, and the connection resistance is greatly increased.